Switch
by Saphirebluelips
Summary: William Herondale belongs with the shadow hunters of his time. Right? So why does he know who Alec is? Clary? And why is Jace Lightwood suddenly having visions of Tessa and Jessamine? Something is going on. But what?
1. Chapter 1

**Hey y'all!**

**I hope you will like my new fanfiction i cooked up! I dont own the characters...god damn it.  
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**But i own this! Wheee! Have fun!  
**

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William Herondale glanced up from the demons spirit as it shattered around him, the green fey looking thing was slowly crumbling away into an ashy grey dust that blew away onto the floor. He wiped the stele off on his black pants and looked around at the mess he had left fighting the demon.

Chairs were turned over and more than a couple windows had been shattered. "I am not cleaning that up." Will said, sticking the stele back into his belt and wiping his hands off on his shirt.

"Alec, come check this out!" the dark haired boy called, smirking and turning, expecting Alec to stride in and reprimand him for making a mess but instead Jem stuck his head through the doorway, grey eyes blinking in confusion. "Uh, Will? Who's Alec?"

Will froze, "Uh…I don't actually…I have no idea." he said in puzzlement, looking around, "Did I say Alec?" he asked and Jem nodded, "Yes, you definitely said Alec." he said, coming to Wills side.

"I must be drunk again." Will muttered, using his long time excuse and putting a hand to his head. Who was Alec?

"Yeah Will, I'm sure." the silver boy said, nodding and rolling his eyes, "Come on, Tessa's waiting outside. It's bad to keep a lady waiting." he said, turning from the room. Will followed, "Tessa?" he asked, tilting his head, "You mean Clary right?" he asked and then shook his head, what was he saying?

Jem turned to Will and stared; bewildered. "Huh? Who?"

Will opened his mouth but then closed it, "Maybe I'm going mad." he said, "Never mind." he said, walking from the room.

Back outside Will pulled his long black coat around him tighter to cut off the cold London wind as it swept through the stone buildings. A red haired girl watched him for a minute and Will locked eyes with her, blue meeting green. "Hey Clary." he greeted the short girl as she hops down from the box she had been sitting on. Clary grinned, "Hey Jace, What's up?"

Suddenly the girl swirled and was replaced with a much taller girl with brown hair curled up into a bun and a long green dress, "Clary?" Tessa asked, raising one delicate eyebrow. Will gaped at the girl, "What? How…? Ug…I think I'm going insane Tess."

"We already knew that." Jem called over his shoulder as he walked to the mouth of the alley and looked around.

"What happened?" Tessa asked him softly, looking concerned, examining his face. "You don't look sick." Will shook his head, "Do you know who Alec is? How about Clary?" he asked, leaning up against the brick wall of the alley.

Tessa narrowed her eyes, "I'm sorry Mr. Herondale but I'm afraid I don't." her voice suddenly cold and she turned away. Will turned to her, "Tessa…?" he asked; hurt. Jem suddenly appeared behind the two, "Carriage is here Miss Tessa." he said, nodding to the alley's opening. Tessa nodded, "Thanks Jem." she said and Will clenched his hands. "Right, so you can call him by his first name but not me." he muttered under his breath. Tessa made her way to the carriage in silence, Jem following her. Who was Clary and why was Will saying her name? Was she a girl he had met or…? Tessa shook her head, it didn't matter.

She climbed into the carriage and sat down on one of the seats. Jem sat beside her and she struggled to keep her eyes open. The boys had been out here since one in the morning and she had volunteered to go with them. That had been a bad idea.

Will glared at Jem as he slid into the seat on the other side of Tessa and her eyes fluttered shut as she slipped down to rest her head on Jem's shoulder. Jem glanced down at the now sleeping girl and smiled softly, reaching over to finger a piece of her hair.

"Jem." Will said, voice hard and Jem jerked, looking quickly away from the girls face. "Yes?" he asked, silver eyes narrowing.

"I need to know who those people are." Will said, putting his fingers to his temple and leaning over and frowning in annoyance. "You mean Alec and…what was it? Clary?" Jem asked. Will nodded, "Yes."

Then he leaned back and closed his eyes, resting his head on the carriage wall.

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At the same time in Manhattan a golden boy opened his eyes.

"What the fuck…?"

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**Ooohhh, Jace? Huh? **

**Im so confused! Well, not really since i wrote it, but _you_ should be!  
**


	2. Chapter 2

**Heres the second chapter! I hope you all liked it so far! **

**Jace time! YAY!  
**

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Jace's eyes flew open and the golden boy lurched up in bed, hand flying to his chest.

"What the fuck…?" he whispered to himself, "Weird dream…" he shook his head and then pushed the white sheets off his legs, sliding off the bed. He worked his shoulders up and down, wincing at the soreness. Training was a bitch yesterday.

There was a knock at his door and Jace rolled his eyes, "One sec." he called, stumbling to the door and looking down at his bare chest. He shrugged and pulled the door open.

A red headed girl burst through the door, her green eyes flashing and Jace grinned; Clary. "Ugh! Alec is pissing me off! Does he –?" she cut off as she spun around to face him, eyes traveling up his bare chest. "Get a shirt." she muttered, averting her eyes, and Jace grinned.

"But you know I look so much better like this." he said, spreading his arms and smirking. Clary rolled her eyes as Jace grabbed a white shirt out of the drawer. "And you were the one who stormed into my room at…" he glanced at the clock, "Eight in the morning. I don't usually sleep in a shirt. Or anything else for that matter…" he added as Clary's cheek flamed and she turned away. "Shut up Jace, don't be gross." and he smirked, chuckling.

"I had a weird dream last night." he told her, shrugging the shirt on.

"Really?"

Jace straightened his shirt and looked up. "What?!" he jerked away from the brown haired girl that was sitting on his bed. He looked concerned and stood, her green dress floating around her, "What's wrong?" she asked, stepping forward.

"Tessa?" Jace whispered. It was the girl from his dream! The one he had been drawn to.

Suddenly his vision flashed and the pretty brown haired girl was replaced by an annoyed looking red head. "Who's Tessa? Another girlfriend?" he asked, sneering and rolling her eyes. She stalked from the room as Jace gaped after her, his rain finally catching up.

"Wait Clary!" he called, grabbing a weapon off the top of his dresser and running after her, "Tessa is not a girlfriend!"

Suddenly Isabelle stepped in front of him and Jace jumped backwards, "Holy – Izzy! How did you…?" he looked around the girls shoulders to see Clary disappear. "Damn it." he muttered and Izzy crossed her arms.

She wore the usual black shadow hunting gear and her hair fell around her shoulders as she crossed her arms, calling Jace's attention back to herself.

"I have a date tonight, can I borrow your dagger?" she asked, smirking and Jace narrowed his eyes, "Huh?" he asked, "A date?" he repeated, sliding a silver knife out of his belt and holding it out to her.

"A date with a demon."

Jace looked up, knife still in hand, and gaped.

"Ew! Why on earth would I want that?" a sickly sweet voice rang out from the girl in front of him. The girl wore a long blue gown with a fair amount of cleavage showing, hair tied up in a curly up-do.

"Who are you?" Jace whispered to the girl and she placed her hands on her hips, "Will, are you spacing out again?" The girl asked and Jace narrowed his eyes. Will…? That was what the man in his dream had called him.

"Who are you?" he asked again, this time more forcefully.

"Jessamine. Stupid." she rolled her eyes and then shoved past him, dress dragging on the floor.

Jace whipped around after her only to see Izzy walking away and the knife was gone from his hand.

"Jace!" Alec's voice came from the end of the hall, "We have a situation!"

Jace looked around to see a silver haired boy running at him, "Will!" he screamed. Jace lurched backwards and his head hit the wall.

And then everything went black.

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Will Herondale smirked at Tessa from across the table, wincing as his head started to ache in pain.

Okay, what is going on?

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**Sooo...you figure out whats going on yet? **

**No?  
**

**Huh.  
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**Well, ya'll know what to do now right? No?  
**

**REVEIW! PLEASE!  
**


	3. Chapter 3

**I am a terrible person to leave you wonderful people waiting!Well, l****alala, here is another installment!**

**Me: I totes own it all bitches... *coucough***

**Jace: You're an idiot you realize.**

**Me: *sigh* I know. I wish I did - but I don't own it. Shit. **

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Will made his way to his room, twisting a silver ring around his hand. His head hurt like hell and he couldn't seem to get his mind off this red haired girl who was always yelling at him on the edge of his conscious.

Bloody hell.

His head started to ache even more and Will scraped his hand down his face, biting his lip. He'd never had a headache this bad. Not even when he's gotten smashed that one night three years ago with that girl and –

"William!"

A light voice carried down the hall and Will flinched, but turned around, sighing as if the very movement was painstakingly difficult.

Tessa hurried to catch up with him, one hand holding up her green skirt as she walked. "Will? Is something the matter? You rushed out of there like Valentine himself was after you!" Tessa said, looking concerned and reaching for his forehead.

Will closed his eyes as Tessa's soft hand touched his forehead, brushing her fingers along and making a 'tut-tut' noise.

Then what she said became apparent.

"Wait, Valentine?" Will looked up and the hand fell away. "Who's Valentine Tessa?"

But Tessa wasn't standing there any more.

In her place, once again, was the tiny red-head, glinting green eyes narrowed at him. "Valentine?" the girl asked, "Don't play dumb you moron. Valentine – the evil guy out for the Mortal Interments…? Ringin' and bells for you Jacie?" the girl said, rolling her eyes.

Will lunged forward, pinning the girl to the wall. She gasped out in shock as Will's hand tightened around her throat.

"_Shit!_ Jace let me go! Jesus!" the girl yelled at him, fighting his grasp.

"Who are you?" Will asked threateningly, leaning forward and staring into her eyes. The girl gaped at him, her face displaying nothing but pure shock.

"Clary!" she gasped out, eyes wide, "It's me Clary! Jace please! It's me!"

Will growled softly; he had already guessed that this girl was Clary.

"Why do you keep calling me that name?" Will continued in a deadly voice, tone lowering to a whisper, "Jace, was it?"

Clary gaped once more, "What else should I call you? Jace _is _your name, right?" she said slowly, starting to tear up from the hand placed on her throat.

Will slowly unhanded the girl, letting her slide down to the floor, rubbing her throat and staring up at him with reproachful eyes.

"No. My name is not Jace; stupid mundane. It's William Herondale." Will glared down at her, "Please explain to me what in gods name you are doing here and what you want from me or so help me I will kill you right now!"

"_Holy shit!_ Jace! _Stop!_"

Izzy ran forward, pushing Jace away from a now freaked Clary, and knelt down to sit beside her, muttering something as she reached out to comfort the girl.

Jace backed away from them, blinking quickly as his hands flexed in and out of a fist. What had he just done?

"What…what happened?" he asked unsteadily, voice breaking.

Clary stood up, rubbing her throat and glaring at him. "You didn't know who I was Jace. You said you were someone called William Herondale." she paused, her voice getting quieter. "And then you threatened to kill me."

Izzy narrowed her eyes at the golden boy, "What the hell is going on Jace…?" she asked slowly, her leather pants tightening as she took a step towards him.

Jace stupidly shook his head, eyes fixed on the red hand print forming around Clary's throat.

Izzy nodded once, taking Clary's arm in hers and fixing Jace with a glare.

"I think we need to go see Magnus."

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**Yay! Magnus next!  
**

**Review my minions! **


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